U.S. Pat. No. 4,001,742 entitled "Circuit Breaker Having Improved Operating Mechanism" describes a circuit breaker capable of interrupting several thousand amperes of circuit current at several hundred volts potential. As described therein, the operating mechanism is in the form of a pair of powerful operating springs that are restrained from separating the circuit breaker contacts by means of a latching system. Once the operating mechanism has responded to separate the contacts, the operating springs must be recharged to supply sufficient motive force to the movable contact arms that carry the contacts.
U.S. Pat. No. 5,424,701 entitled "Operating Mechanism for High Ampere-Related Circuit Breaker describes an operating mechanism capable of immediately resetting the circuit breaker operating mechanism to reclose the contacts without having to recharge the circuit breaker operating springs immediately after opening the circuit breaker contacts.
When such circuit breakers are exposed to short circuit overcurrent conditions, the powerful magnetic forces of repulsion generated between the moveable and fixed contacts within any one of the circuit breaker poles, overcomes the holding forces of the contact springs and "blows" the moveable contact to the contact OPEN condition.
The circuit breaker operating mechanism, that controls the ON and OFF states of the circuit breaker contacts is designed for a particular circuit breaker ampere rating. If one such operating mechanism is used within higher than rated circuit breaker applications, it has been determined that the contacts may "blow open" upon overcurrent occurrence that is lower than short circuit.
It would be economically advantageous to be able to use a common circuit breaker operating mechanism over a wide range of circuit breaker ratings without having to adjust the circuit breaker holding springs to compensate for higher ampere ratings.
The purpose of this invention is to provide a mechanical linkage arrangement between the circuit breaker operating mechanism and the movable contact arms. The linkage being capable of retaining the circuit breaker movable contact arms from separating the circuit breaker contacts during quiescent current conditions while insuring rapid contact separation upon the occurrence of a short circuit overcurrent condition.